Device for stretching case ribbons of plastic material

ABSTRACT

A device for stretching case ribbons of plastic material, having a clamping device for the one ribbon end, a cutting device and stretching mechanism for the other ribbon end and an actuating lever for the stretching mechanism and cutting device, the device being made of simple and cheap molded plastic parts combined with stamped metal parts, and said clamping device having clamping jaws of which the one only is toothed thereby allowing easy operation of the clamping device and careful treatment of the ribbon.

United States Patent Styner I 51 May 16, 1972 DEVICE FOR STRETCHING CASE RIBBONS OF PLASTIC MATERIAL inventor: Rudolf Styner, Frauenkappelen, Switzerland Strapex A. G., Wohlen, Switzerland Mar. 16, 1970 Assignee:

Filed:

Appl. No.:

Foreign Application Priority Data Mar. 20, 1969 Switzerland ..4201/69 US. Cl. ..140/123.6, 140/932 Int. Cl.

Field of Search ..140/93.2, 93.4, 123.6; 254/51; 100/29, 30, 32

References Cited UNITED STATES PATENTS 2,156,062 4/1939 Porter... ..254/5l 3,129,728 4/1964 Sharko 3,369,851 2/1968 Perryetal. ..64/1

Primary Examiner-Lowell A. Larson Attorney-Imirie and Smiley [57] ABSTRACT A device for stretching case ribbons of plastic material, having a clamping device for the one ribbon end, a cutting device and stretching mechanism for the other ribbon end and an actuating lever for the stretching mechanism and cutting device, the device being made of simple and cheap molded plastic parts combined with stamped metal parts, and said clamping device having clamping jaws of which the one only is toothed thereby allowing easy operation of the clamping device and careful treatment of the ribbon.

12 Claims, 3 Drawing Figures Patented May 16, 1972 2 Sheets-Sheet l M mm, ,mm

I)! "TOR.

Patented May 16, 1972 2 Sheets-Sheet 2 mm mw m: 3

INVENTOR.

1 V DEVICE FOR STRETCHING CASE RIBBONS'OF PLASTIC substantial load, it being necessary toztempersuch parts.

Therefore, no possibility was found in the past for simplifying the construction and reduce the price. The clamping devices of prior stretching devices are unsatisfactory because they tend to damage the ribbon and require high actuating forces.

It is an object of this invention to overcome these disadvantages of prior devices. The device according tothis invention basically differs from the prior devices in thatsaidclamp ing device and stretching mechanism have shafts of plastic material interconnected. with metallic actuating parts, said. cutting device has a cutting blade mounted in a'support of plastic material, and saidclamping device has afirsteccenterlike rotatable clamping jaw and a second clamping jaw, the clamping surface of the. second clamping jaw only being toothed for improving the clamping effectr'l'herefore, instead, of the expensive and heavy turned and cast metallic parts of prior devices, cheap and relatively lightparts of-plastic material and stamped metal parts mayibe used,whereby combination of such parts is feasible such that allparts are suitable for the stresses acting on them. By the use. of-plastic parts and stamped parts the weight may substantially be reduced.

The clamping device is reliable without damaging the ribbon and it may easily be operated. Preferably said second clamping jaw may be displaceable between stops in a direction transversal to the clamping force, and it may be urged or restored into a rest position by a spring. In" this way afurther substantial improvement of the clamping action,.careful1 treatment of the ribbon and easei'n operation may be obtained.

This invention will now be explained in detail with reference to the accompanyingdrawing illustrating by way of example an embodiment of the stretchingdevice. 7

FIG. 1 is a side view,

FIG. 2 is a partial vertical section and FIG. 3 is a partial horizontal section of the device.

The illustrated device has a frame made of stampedparts, including a base plate 1 and an extension 2 serving-as a'handle and support. The frame has two side walls 3 and 4and thus has substantially U-shaped crosssection. The movable parts of the device are mounted on side walls 3 and 4.

The clamping device for the one end 5' of the case ribbon 5 to be stretched and indicated in dash-dotted lines, has a shaft 6' of plastic material pivoted in side walls 3 and 4. Outside the side wall 3 the shaft has a clamping jaw 7 witha slightly eccentric smooth clamping surface 7'. The clamping jaw 7 is located above the toothed rear end of a second stamped clamping jaw 8 mounted in a slider 9 of plastic material. A resetting spring 10 usually urges the slider 9 into the rest position shownin FIG. 1. This end position of the slider 9 and its opposite end position are determinedby abutment of the: bentnose of the clamping jaw 8 against the end surfaces of a-window ll of plate 1. The slider 9 is guided and anchored to the plate 1 by means of a disc 12.

The shaft 6 has a coarse external toothing 13 atan end portion thereof. Cam rings 14 having a corresponding inner toothing engaging the external toothingof the shaft 6.are mounted on shaft 6. The cam rings 14 are axially secured between a shoulder of the shaft and the side wall-4. As shown in FIG. 2, the cam rings have a nose 1'5 and an extension 16. An anchoring pin 17 for the one end of acoil spring l8 wound onto shaft 6 is riveted to the extension 16. The other end of spring 18 is supported on the base plate 1 so that spring 18 tends to turn cam rings together with shaft 6 in counterclockwise direction, whereby the eccentric clamping surface 2 7' is swung downwardly against the. toothed portion of the lowerclamping jaw 8.

By means of bushings 21 a stretching or spanning shaft 22 of plastic material is pivotably mounted in side walls 3 and 4. It-

has an external toothingr23-similar to toothing 13. Stamped discs 24-having an extemal. ratchet toothing engage the toothing 23 of shaft 22 with an intemaltoothing and are thus fixed on shaft 22. Discs 24 are axially secured between a shoulder of shaft 22 and a ring 25' shifted ontoshaft 22, whereby shaft22 is itself axially secured by means of a button 26. of plastic material held in'the hollow end portion of shaft 22' by a snap joint. The free end of shaft; 22 extending outwardlyfrom side wall 3 has an external toothing and a diametral slit 27 allowing insertion of the one end of ribbon 5 with little clearance.

A stamped actuating lever 29 ispivotably mounted on shaft 22 and a ring 25 shifted thereon by means of two annular. lugs 28.-Two metal sheets welded to theinside of the actuating lever form-a recess 31 slightly relieved at one end, into which a stepping pawl 32 and a V.-shaped leaf spring 33 maintaining pawl 32 inengagement withthe ratchettoothing of discs 24 are loosely inserted andmounted in recess 31. Spring 24 engages a stop nose 34 formedimthe stepping pawl 32. A stop pawl 35 withleaf spring 36 is mountedin a similar manner on the base plate 1.

A-blade support 38-of plastic materialis fixed on the frame. It has a lateral slit 39 for receiving the ribbons, and a cutting blade 40 witha slit 41 is molded into the support 38 within reach of slit 39. A cutting shaft 42 is pivoted in a longitudinal bore ofthe blade support 3 8, this shaft 42 engaging blade 40. without clearance within reach of a slightly inclined surface ground on shaft 42 and forming a cutting edge 43. The other endof the cutting shaft 42 is pivoted in side wall 4. Inside the bearing in side wall 4 shaft 42 has a plane cuttings 44. Two similar stamped discs 45 having each'a nose 46 and ahole of a form similar to the cross section of the shaft 42 withinreach of the, cuttings 44 are mounted on shaft 42. Discs 45 form an actuating cam of which the nose 46 extends into a gap 47 of the one ring 28 of the actuatinglever 29. The illustrated rest position of discs 45 and of the cutting shaft 42 is determined by engagement of the one straight edge portion of discs 45 with the base plate 1. j

' When the actuating lever 29 isin its lower end position as illustrated, a downwardly extending nose 48 of the same engages extension 16forrned by rings. 14 and thereby maintains such rings and shaft 6 in the illustrated position in which the clamping surface 7' is lifted off the lower clamping jaw 8.

- When the device is in its initial position as illustrated, the one end 5' of the case ribbon is inserted between the clamping jaws 7 and ,8 and below theblade support 38. The other end 5" of the ribbon is inserted into the slit 38 of the blade support 38 and into the slit 4l of the blade 40 respectively, and then into the slit 27 of the stretching shaft 22. A seal 49 is applied onto the overlapping ribbon ends, thisseal being closed after stretching of the ribbon in the manner set out hereafter. If possible, the seal may also be applied after stretching. In order to stretch the ribbon, the actuating lever 29is lifted. Its nose 47' first releases extension 16 and the clamping shaft 6 is turned in counterclockwise direction by spring 18. Hereby the clamping surface 7' of the clamping jaw 7 is pressed against the toothed portion of the lower clamping jaw 8 where by the ribbon end 5' is firmly clamped between jaws 7 and 8. Lifting of the actuating lever 29 has caused rotation of the stretching shaft 22 in counterclockwise direction due to transmission of the lever movement through pawl 32 and discs 24. By repeated oscillating movement ofthe actuating lever 29 within a range for which neither the cutting device is actuated through discs not the clamping shaft is rotated through extension 16, the stretching shaft-is further rotated stepwisein clockwise I Since the ribbon cannot slide on the toothing of the clamping jaw 8, damaging and weakening of the same is avoided. Indentation of ribbon by the toothing of clamping jaw 8 only occurs at the inner side of the tape and is not visible. When the ribbon is sufficiently stretched, the seal 48 is closed, whereafter the lever 29 is turned in anticlockwise direction until the nose 46 of disc 45 abuts against the one end of the gap 47 and is turned together with discs 45 and cutting shaft 42 in clockwise direction. The ribbon end 5" is thereby cut off by interaction of one cutting edge formed at the slit 41 of blade 40 and the cutting edge 43 of cutting shaft 42. The tape end now gets loose on the stretching shaft and may be removed from the same. The actuating lever 29 is now rotated downwardly into the illustrated initial position, whereby its nose 47 engages the extension 16 and turns the clamping shaft 6 back into its illustrated inoperative position. The clamping jaw 7 is thus lifted off the clamping jaw 8 and the ribbon portion 5' may now be removed from the device. Returning of the clamping jaw 7 from its clamping position into its illustrated initial position is substantially facilitated by the smooth claming surface 7' sliding on the ribbon and the possibility to shift the lower clamping jaw 8 back from its clamping position.

What I claim is:

l. A device for stretching case ribbons of plastic material, comprising a clamping device for the one end of a ribbon, a cutting device and a stretching mechanism for the other end of said ribbon and an actuating lever for these parts, a frame made of stamped parts, said clamping device and stretching mechanism having each a shaft of plastic material joumaled in said frame and having portions of non-circular cross section carrying stamped metallic actuating part with apertures of a non-circular shape non-rotatively engaging said portions of non-circular cross section, said cutting device having a cutting blade mounted in a support of plastic material, and said clamping device having a first eccenter-like rotatable clamping jaw on said shaft of the clamping device and a second clamping jaw mounted on said frame the clamping surface of the second clamping jaw only being toothed for improving the clamping effect while the eccentric clamping surface of said rotatable clamping jaw is smooth.

2. A device according to claim 1, wherein said second clamping jaw is displaceable between stops in a direction transversal to the clamping direction of said jaws, said second clamping jaw being loaded by a spring urging it into an end position.

3. A device according to claim 1, wherein said rotating shaft of said clamping device is pivoted in side portions of said stamped frame and carries a clamping ring on an eccentric shaft portion projecting at one side of the frame.

4. A device according to claim 3, wherein said rotating shaft of the clamping device has an external toothing carrying a stamped actuating cam ring having an internal toothing engaging said external toothing.

5. A device according to claim 4, wherein said actuating cam ring has an anchoring pin for a clamping spring.

6. A device according to claim 1, wherein said shaft of the stretching mechanism has an external toothing carrying at least one stamped disc having an outer ratchet toothing and an internal toothing engaging said external toothing of the shaft.

7. A device according to claim 6, comprising a stepping pawl and a stop pawl engaging said outer ratchet toothing and loosely inserted and anchored in recesses of said actuating lever and frame respectively.

8. A device according to claim 1, wherein shafts of the clamping device and stretching mechanism are secured against axial displacement by means of stop buttons of plastic material attached to their hollow end portions by snap joints.

9. A device according to claim 1, wherein said support of the cutting member has a slit adapted for receiving said other end of said ribbon and a cutting blade molded into said support in a position transversal to said slit.

10. A device according to claim 9, wherein said cutting member is a cutting shaft rotatably mounted in said sugport and engaging said cutting blade, an inclined surface emg formed on said cutting shaft within reach of said cutting blade, the one edge of said inclined surface constituting a cutting edge for cooperation with said cutting blade.

11. A device according to claim 10, comprising a stamped actuating cam fixed on said cutting shaft and adapted to be operated by said actuating lever.

12. A device according to claim 11, wherein said actuating cam has a nose engaging with play a gap in a control portion of said actuating lever such that the actuating lever may swing through a limited range without actuating the cutting device.

t l i 

1. A device for stretching case ribbons of plastic material, comprising a clamping device for the one end of a ribbon, a cutting device and a stretching mechanism for the other end of said ribbon and an actuating lever for these parts, a frame made of stamped parts, said clamping device and stretching mechanism having each a shaft of plastic material journaled in said frame and having portions of non-circular cross section carrying stamped metallic actuating part with apertures of a non-circular shape non-rotatively engaging said portions of non-circular cross section, said cutting device having a cutting blade mounted in a support of plastic material, and said clamping device having a first eccenter-like rotatable clamping jaw on said shaft of the clamping device and a second clamping jaw mounted on said frame the clamping surface of the second clamping jaw only being toothed for improving the clamping effect while the eccentric clamping surface of said rotatable clamping jaw is smooth.
 2. A device according to claim 1, wherein said second clamping jaw is displaceable between stops in a direction transversal to the clamping direction of said jaws, said second clamping jaw being loaded by a spring urging it into an end position.
 3. A device according to claim 1, wherein said rotating shaft of said clamping device is pivoted in side portions of said stamped frame and carries a clamping ring on an eccentric shaft portion projecting at one side of the frame.
 4. A device according to claim 3, wherein said rotating shaft of the clamping device has an external toothing carrying a stamped actuating cam ring having an internal toothing engaging said external toothing.
 5. A device according to claim 4, wherein said actuating cam ring has an anchoring pin for a clamping spring.
 6. A device according to claim 1, wherein said shaft of the stretching mechanism has an external toothing carrying at least one stamped disc having an outer ratchet toothing and an internal toothing engaging said external toothing of the shaft.
 7. A device according to claim 6, comprising a stepping pawl and a stop pawl engaging said outer ratchet toothing and loosely inserted and anchored in recesses of said actuating lever and frame respectively.
 8. A device according to claim 1, wherein shafts of the clamping device and stretching mechanism are secured against axial displacement by means of stop buttons of plastic material attached to their hollow end portions by snap joints.
 9. A device according to claim 1, wherein said support of the cutting member has a slit adapted for receiving said other end of said ribbon and a cutting blade molded into said support in a position transversal to said slit.
 10. A device according to claim 9, wherein said cutting member is a cutting shaft rotatably mounted in said support and engaging said cutting blade, an inclined surface being formed on said cutting shaft within reach of said cutting blade, the one edge of said inclined surface constituting a cutting edge for cooperation with said cutting blade.
 11. A device according to claim 10, comprising a stamped actuating cam fixed on said cutting shaft and adapted to be operated by said actuating lever.
 12. A device according to claim 11, wherein said actuating cam has a nose engaging with play a gap in a control portion of said actuating lever such that the actuating lever may swing through a limited range without actuating the cutting device. 